Refining pressure distillate



Dec.. 17, 11940.. W T; HANCQCK REFINING. PRESSURE DiS-'FILMTE' F iled;Ja-IL- '14 1939 2 Sheets-Sheet, l

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lill/*en for. William Ziazz'oc/k.

l l l l SNN Dec. 17, 1940. w. T. HANCOCK REFINING PRESSURE DISTILL'ATE 2sheets-sheet l2 Filed Jan. 14, 1939 'Inllll'n 'll'.llll

lllllll l l I l I l l Rn Patented Dec. 17, 1940 UNITED STATES PATENTOFFICE 11 Claims.

This invention has to do with the treatment o-f cracked petroleumdistillate by methods of the general type disclosed in my copendingapplication Serial No. 161,954, filed September 1, 1937,

on Process for rening cracked petroleum distillate, and has for itsprimary object to provide certain improvements whereby it is possible toincrease substantially the percentage of sulphur removal from thegasoline content of the pressure distillate.

In accordance with the general method used in the present system, asWell as that described in my copending application referred to above,pressure distillate containing a gasoline fraction is first subjected topolymerization and then admixed with a heated heavier oil, such as fueloil or crude oil, containing hydrocarbons having a substantially higherboiling range than the gasoline fraction contained in the pressuredistillate. As more fully explained in my earlier application,polymerization of the pressure distillate has the general effect ofplacing gum-forming and sulphur containing compounds in a conditionwhereby they are removable in the heavier oil by virtue of its solventaction and Aaffinity for such compounds. After the pressure distillateis intimately admixed with the heated heavier oil, the gasoline fractionis distilled oif, leaving the gum-forming and sulphur containing bodiesto be removed from the system in the heavier oil. Among the outstandingadvantages of the method are that it produces a final distillateunusually low in gums and sulphur and of stable water white color,without necessitating acid treatment, and

the adaptability of the system for blending straight run and crackeddistillate by using, as a heavier oil, a crude oil containing gasoline.

As previously indicated, my present principal object is to providecertain improvements whereby it is possible to remove a substantiallyhigher percentage of sulphur compounds from the gasoline fraction of thepressure distillate. It has been found by fractional distillation of thepolymerized pressure distillate gasoline, and sulphur analyses of theindividual fractions, that the sulphur content increases as thegravities or boiling temperatures of the fractions increase. Analysis of20% fractions shows the sulphur content 50 to increase from 0.30% in thelightest, or lowest boiling fraction, to 1.45% in the heaviest orhighest boiling fraction. Tests also indicate that the sulphur contentof individual fractions increases disproportionately as their gravitiesincrease; that is, the relative increase of sulphur percentage isgreater as the gravities of the fractions increase.

I have found that the ultimate sulphur reduction in the pressuredistillate can be further decreased to unusually low values by `animprove- 5 ment in the type of process of my co-pending applicationreferred to above, whereby after initial polymerization and solvent oiltreatment of the pressure distillate, the latter is fractionated toseparate one or more heavy fractions, the sul- 10 phur content of whichmay be relatively high as compared with the sulphur content of thelighter fractions. The heavy fraction or fractions then arere-polymerized, admixed with the heavy sola vent oil and distilledtherefrom, further depleted '15 of their sulphur content. The treatedvaporized heavier fractions then may be combined and finally condensedwith the lighter fractions, or the retreated heavier and once treatedlighter fractions' may be condensed separately and then` 20 combined orfinally handled in any desired manner. In this way I am able, byretreating the heavier and higher sulphur-containing portion of thepressure distillate gasoline fraction, to obtain a final gasolineproduct of loW sulphur con-' 25 tent.

The invention will be understood to better advantage Without necessityfor further preliminary discussion, from the following description of ytreating systems illustrative of the inventionv in: certain typicalforms. Throughout the description reference is had to the accompanyingdrawings in which:

Fig. 1 illustrates diagrammatically and in flow sheet form a preferredsystem embodying the in Vention; and

Fig. 2 illustrates a variational form of the invention.

Referring rst to the system shown in Fig. 1,

the pressure distillate to be treated may be de- 40 rived from anysuitable source, for example, from, storage through line I0 leading tothe heater II through which the distillate is forced by pump I2 andheated to a suitable polymerizing temperature, which will ordinarilyrange above 200 F., to temperatures around 350 F. to 400 F. or above,depending upon the method of polymerization used. Instead of taking thepressure distillate from storage, it may be passed directly from acracking plant (not shown) at a temperature as indicated above, throughline I3, connecting with pipe I4 leading to the polymerizing chamber I5.The heated pressure distillate may be subjected to polymerization by anysuitable known method, typically and preferably by passing thedistillate through a body of adsorptive material, such as fullers earthlcr Muroc clay, contained within the chamber I 5.

The purpose of subjecting the pressure distillate to polymerization isto remove the gumforming constituents of the oil, and to place thegum-forming and sulphur-containing compounds in a condition whereby theyare rendered removable by the heavier oil admixed with the distillate.This heavier solvent oil may consist of any suitable oil or petroleumfraction heavier than the gasoline fraction contained in the pressuredistillate. Generally speaking, I prefer to use as the heavier solventoil, fuel oil, or a crude oil containing in addition to gasoline, lowerboiling fractions including fuel oil and heavier hydrocarbons.

Where the heavier oil is not otherwise heated, it may be discharged bypump I6 through a heater I1 wherein the oil is heated to a temperaturethat preferably is higher than the normal Vaporizing temperature of atleast the lighter gasoline fractions in the polymerized pressuredistillate. By supplying additional heat to the admixed oils, as laterdescribed, the temperature of the oil leaving heater I1 may be as low asaround 300 F., although it is preferred to heat the oil to asubstantially higher temperature, ranging, for example, between 450 F.to 550 F. or higher. The heated solvent oil is discharged through lineI8 into an enlarged chamber I9 wherein the oil is thoroughly admixedwith the polymerized pressure distillate flowing to the mixer throughline 20. In chamber I9, the two oils are thoroughly commingled, andpermitted to remain over a period of time sumcient to permit maximumdissolution of the pressure distillate gum-forming and sulphur compoundsin the heavier oil. The admixed oils are at the same time maintainedunder pressure sufficient to keep at least the major portion of thegasoline fractions in liquid phase. To effect maximum removal ofgum-forming and sulphur compounds, it is ordinarily preferred to mixwith the pressure distillate from two to four times its Volume of theheated heavier oil.

The admixed oils are discharged through line 2| into a separating zoneor fractionating column 22 wherein the fractions lighter than fuel oil,or lighter than any other predetermined base fraction heavier thangasoline, are vaporized and separated from the unvaporized residuum,which may be removed to storage through line 23. Valve 24 may be set toreduce the pressure of the admixed oils entering the fractionatingcolumn, to an extent suicient to eiTect partial or complete vaporizationof the lighter fractions by virtue of the pressure reduction and theheat contained in the oils. That is to say, the temperature of theheavier oil may be raised sufIiciently in the heater |1 to supply theheat necessary for complete vaporization of the lighter fractions beyondthe valve 24, or in the event of only partial vaporization beyond thatpoint, further heat to complete the vaporization of the lighterfractions may bev supplied by suitable means such as a heating coil 25in the base of the fractionating column.

The vapors are passed from column 22 through line 26 into fractionatingcolumn 21 within which the vapors are subjected to partial condensationfor the purpose of separating the entire gasoline fraction into alighter vaporized portion leaving the fractionating column through aline 28, and a heavier condensed or liquid portion which, to-

gether with any heavier than gasoline fractions carried over fromfractionating column 22, are removed through line 29. It is to beunderstood that the gasoline vapors may be subjected to fractionalcondensation to produce any desired number of condensed cuts orfractions to again be mixed with the heavier oil, although in thespecific system illustrated, I have shown only a single fractionatingstage in which the gasoline content of the oils is subjected to simplefractionation to produce a single lighter vaporized portion, and asingle heavier cut.

The condensate taken from fractionating column 21 through line 29 isagain admixed with the heated heavier oil, which may be supplied fromany suitable source, for example, through line 30 connecting with theheater discharge line I8, the single heater I1 serving to preheat theheavier oil introduced in both mixers I9 and 3|. The heavier oil to beadmixed with the heavy gasoline fraction may, on the other hand, betaken from a source independent of the heavier oil supplied in mixer I9.Accordingly, I have shown an independent supply line 32 through whichpreheated heavier oil may be taken from a suitable source other than thesupply for heater I1. It will be understood, therefore, that theso-called heavier oil used in the initial treatment of the polymerizedpressure distillate in mixer I9, and later in the treatment of theheavier portion of the gasoline fraction in the mixer 3|, may consist ofoils derived from the same or independent sources, although in eachinstance the solvent oil will have a boiling range substantially higherthan the boiling range of the heaviest gasoline fractions being treated.

The heavier portion of the gasoline fraction withdrawn from column 21through line 2B preferably is again heated to suitable polymerizingtemperature, say in the neighborhood of from 300" F. to 375 F., bypassage through the heater 33. The oil is then again subjected topolymerization by any suitable method, as by passing the oil while forthe most part in liquid phase, through chamber 34 and in direct contactwith adsorptive clay contained therein. Where the temperature of the oilleaving the fractionating column 21 is sufficiently high for purposes ofpolymerization, the heater 33 may be ley-passed by discharging the oildirectly through line 29a to the polymerizing chamber.

The polymerized heavy portion of the gasoline ilowing through line 35,together with solvent cil from either of lines 30 or 32, is forced bypump 36 into the mixer 3| wherein the oils are intimately commingled, aspreviously explained with reference to the mixer I9. As before, theproportion of the heavier oil introduced to the mixer is substantiallylarger than the gasoline fraction, and during the mixing the oils aremaintained under pressure such that the major portion of the gasolinewill remain in liquid phase. From the mixer, the oils are dischargedthrough line 31 into fractionating column 38, valve 39 being set toreduce the pressure of the oils so that the gasoline fraction willvaporize by virtue of the pressure reduction. Additional heat may besupplied by the heating coil 4D to completely vaporize the gasoline,where the heat content of the admixed oils and the pressure reduction atvalve 39 are in themselves insuflicient to produce flash vaporization ofthe entire gasoline content of the admixed oils.

The unvaporized oil in the base of fractionating column 38, which mayconsist of kerosene distillate or perhaps other heavier hydrocarbonsdepending upon the point of fractionation in column 22, together withthe unvaporized heavy oil introduced to the mixer 3|, is removed tostorage through line 4|. The vaporized heavier portion of the pressure-distillate gasoline fraction may be separately condensed, or combinedwith the vaporized lighter portion of the gasoline fraction leaving thefractionating column 21. As illustrated, this vaporized lighter fractionmay be taken separately from line 28 through line 42 to the condenser43, or it may be discharged through line 44, combined with the vaporizedheavy gasoline fraction leaving column 38 through line 38a, and bothfractions then passed through line 45 to the condenser 46 and thedistillate receiver 41. On the vother hand, where the lighter `gasolinefraction is separately condensed in condenser 43, the heavier vaporizedfraction leaving column 38 may be separately subjected to furtherfractionation and condensation by discharging the vapors through line 48into fractionating column 49, then passing the vapor fraction throughlines 5|) and 45 to the condenser 46. Condensate is removed from thebase of fractionating column 49 to storage through line 5|. As a furtheralternate method of operation, the vaporized lighter gasoline fractionin line 44 may be combined with the vaporized heavier fraction leavingfractionating column 38 (by closing valve 5| and opening valves 52 and53), and both vapor fractions then subjected to fractionation in column49 and final condensation in the condenser 46.

The form of the invention shown in Fig. 2 is similar to the previouslydescribed system in its treatment of the oils and vapors up to the vaporline 25, and therefore need not again be described .beyond theapplication of the same reference numerals to corresponding parts. Thesystem shown in Fig. 2 differs principally from that of Fig. 1 in thatthe clay treated vapors after leaving fractionating column 22 and beingpassed through clay chamber |21 to remove impurities, ow through line|28 to the fractionating column |44 wherein the vapors are fractionallycondensed to separate the lighter and heavier portions vof the gasolinefraction, and to separate said heavier portion from'lower boiling heavyends. The heavier portion of the gasoline fraction, instead of beingseparately mixed with .the heavier solvent oil, is returned to thepolymerizing chamber I5 and to the mixer I9.

The vapors from line |28 are discharged into a lower section |44a of thefractionating column |44, in which the entire gasoline fraction isseparated from the hydrocarbons heavierthan gasoline by condensation ofthe latter, the distillate being removed to storage through line |45.Any additional heat necessary for the fractionation may be supplied byheating coil |46 in the base of the fractionating column. The vaporizedgasoline fraction passes upwardly through riser |41 and the imperforateplate |48 into the upper section |44b of the fractionating column,wherein a heavier portion of the gasoline fraction is condensed, leavingthe vaporized lighter portion to flow through linel |49 to condenser |50and the distillate to receiver l5. Half or any other suitable fractionof the condensed heavier portion of the gasoline may be removed throughline |52 to the receiver, while the condensate remaining is returnedthrough lines |53 and |54 to be recirculated directly to and through thepolymerizing chamber I5, or, via line |55, to the heater Il and thenthrough the polymerizing chamber. I'he recirculated fraction is againpolymerized and-thus combined with the polymeriz'ed pressure Vdistillateflowing through line 2D tothe mixer; 5

-In' both described forms of the invention, the lentire gasolinefraction contained in the polymerized pressure distillate rst is admixedwith the heavier oil, then vaporized, leaving gumforming andsulphur-containing compounds vin 10 thev heavier oil. Thereafter, aheavier portion of the gasoline fraction containing sulphur cornpoundsin higher percentage than the lighter portion of the gasoline fraction,is again subjected to polymerization and admixed with the 15 heavier oilfor further removal of the undesirableand contaminating bodies. It willbe understood that the lighter and heavier portions of the gasolinefractions referred to in the foregoing, may include gasoline cuts withinany suitable or predetermined boiling range. The particular point offractionation may depend upon the sulphur content of relatively lighterand heavier portions of the pressure distillate gasoline, as determinedby fractionation and sulphur analysis of the individual fractions. Togive a typical example, the lighter fraction may consist of hydrocarbonsboiling below 250 F., the heavier portion comprising the remainder ofthe gasoline range.

I claim:

l. 'I'he process of refining pressure distillate that includes,subjecting gasoline-containing heated cracked petroleum distillate topolymerization by contact with adsorptive material, heating heavier oilhaving a substantially higher boiling range than the gasoline content ofsaid distillate, mixing the polymerized distillate with the heatedheavier oil, vaporizing said gasoline from the heavier oil to leave partof the gum-forming and sulphur compounds of the gasoline in said heavieroil, separating a lower boiling fraction of the gasoline from a higherboiling fraction thereof, again polymerizing said higher boilingfraction of the gasoline by contact with adsorptive material and thenmixing the polymerized fraction with heated heavier oil, vaporizing saidhigher boiling fraction from the last mentioned heavier oil, leavingadditional gum-forming and sulphur-containing compounds in the heavieroil, f and condensing the vaporized fractions of said gasoline.

2.r The process of refining pressure distillate that includes,subjecting gasoline-containing heated cracked petroleum distillate topolymer- 55 ization by contact with adsorptive material, heating heavieroil having a substantially higher boiling range than the gasolinecontent of said distillate to a temperature in excess of about 300 F.,mixing the polymerized distillate with the heated heavier oil,vaporizing said gasoline from the heavier oil to leave part of thegum-forming and sulphur compounds of the gasoline in said heavier oil,separating a lower boiling fraction of the gasoline from a higherboiling fraction thereof, 65 heating and polymerizing said' higherboiling fraction of the gasoline by contact with adsorptive `materialand then mixing the polymerized fraction with heated heavier oil,vaporizing said higher boiling fraction from the last mentioned heavieroil, leaving additional gum-forming and sulphur-containing ycompounds inthe heavier oil, andA condensing the vaporized fractions of saidgasoline.

3. The process of rening pressure distillate 75 that includes,subjecting gasoline-containing heated cracked petroleum distillate topolymerization by contact with adsorptive material, heating heavier oilhaving a substantially higher boiling range than the gasoline content ofysaid distillate, mixing the polymerized distillate with the heatedheavier oil, further heating the mixed oils and vaporizing said gasolinefrom the heavier oil to leave part of the gum-forming and sulphurcompounds of the gasoline in said heavier oil, separating a lowerboiling fraction of the gasoline from a higher boiling fraction thereof,polymerizing said higher boiling fraction of the gasoline by contactwith adsorptive material and then mixing the polymerized fraction Withheated heavier oil, vaporizing said higher boiling fraction from thelast mentioned heavier oil, leaving additional gum-forming andsulphur-containing compounds in the heavier oil, and condensing thevaporized fractions of said gasoline.

4. The process of refining pressure distillate that includes, subjectinggasoline-containing heated cracked petroleum distillate topolymerization by passing the distillate through a stationary body ofadsorptive material, heating heavier oil having a substantially higherboiling range than the gasoline content of said distillate, mixing thepolymerized distillate with the heated heavier oil, vaporizing saidgasoline from the heavier oil to leave part of the .gum-forming andsulphur compounds of' the gasoline in said heavier oil, separating alower boiling fraction ofthe gasoline from a higher boiling fractionthereof, polymerizing said higher boiling fraction of the gasoline bycontact with adsorptive materialand then mixing the polymerized fractionwith heated heavier oil, vaporizing said higher boiling fraction fromthe last mentioned heavier oil, leaving additional gum-forming andsulphur-containing compounds in the heavier oil, and condensing thevaporized fractions of said gasoline.

5. The process of rening pressure distillate that includes, subjectinggasoline-containing heated cracked petroleum distillate topolymerization by contact with adsorptive material, heating heavier oilhaving a substantially higher boiling range than the gasoline content ofsaid distillate, mixing the polymerized distillate with one stream ofthe heated heavier oil, passing the mixed oils into a separating zoneand vaporizing said gasoline from the heavier oil admixed therewith toleave part of the gum-forming and sulphur compounds of the gasoline insaid heavier oil, removing the heavier oil from the separating zone,separating a vaporized lower boiling fraction of said gasoline from anunvaporized higher boiling fraction thereof, polymerizin-g said higherboiling fraction of the gasoline by contact with adsorptive material andthen mixing the polymerized higher boiling fraction with another streamof said heated heavier oil separate from the first mentioned stream ofheavier oil, vaporizing said higher boiling fraction of the gasolinefrom the heavier oil admixed therewith, leaving additional gum-formingand sulphur-containing compounds in the heavier oil, and condensing thevaporized fractions of said gasoline.

6. The process of rening pressure distillate that includes, subjectinggasoline-containing heated cracked petroleum distillate topolymerization by contacting it with adsorptive material, heating aheavier oil having a substantially higher boiling range than thegasoline content of said distillate, mixing the polymerized distillatewith the heated heavier oil, passing the mixed oils into a separatingzone and vaporizing said gasoline from said heavier oil to leave part ofthe gum-forming and sulphur compounds of the gasoline in said heavieroil, removing the heavier oil from the separating zone, separating avaporized lower boiling fraction of said gasoline from an unvaporizedhigher boiling fraction thereof, heating and polymerizing said higherboiling fraction by contacting it with adsorptive material, then mixingsaid higher boiling fraction with heated heavier oil, vaporizing saidhigher boiling fractionfrom the heavier oil admixed therewith in asecond separating zone to leave additional gum-forming andsulphur-containing compounds in the heavier oil, Withdrawlng theunvaporized heavier oil from said second separating zone, and condensingthe Vaporized ,fractions of said gasoline.

7. The process of rening pressure distillate that includes, subjectinggasoline-containing heated cracked petroleum distillate topolymerization by contacting it with adsorptive material, heatingheavier oil having a substantially higher boiling range than thegasoline content of said distillate, mixing the polymerized distillatewith the heated heavier oil, passing the mixed oils into a separatingZone and vaporizing said gasoline from said heavier oil to leave part ofthe gumforrning and sulphur compounds of the gasoline in said heavieroil, passing the vaporized gasoline through a body of adsorptivematerial, removing the heavier oil from the separating zone, separatinga vaporized lower boiling fraction of said gasoline from an unvaporizedhigher boiling fraction thereof, polymerizing said higher boilingfraction by contacting it with adsorptive clay and then mixing saidhigher boiling fraction with said heated heavier oil, vaporizing saidhigher boiling fraction from the heavier oil admixed therewith, leavingadditional gum-forming and sulphurcontaining compounds in the heavieroil, and condensing the vaporized fractions of said gasoine.

8. The process of refining pressure distillate that includes, subjectinggasoline-containing heated cracked petroleum distillate topolymerization by passing it through a treating zone containingadsorptive material, heating heavier oil having a substantially higherboiling range than the gasoline content of said distillate, mixing thepolymerized distillate with the heated heavier oil, passing the mixedoils into a separating zone wherein said gasoline is vaporized from saidheavier oil to leave part of the gum-forming and sulphur compounds ofthe gasoline in said heavier oil, removing the heavier oil from theseparating zone, separating a vaporized lower boiling fraction of saidgasoline from an unvaporized higher boiling fraction thereof, furtherdepleting said higher boiling fraction of the gasoline of its gumiormingand sulphur compounds by returning it to said treating zone wherein itis again polymerized together with the pressure distillate passingtherethrough and later vaporized from said heavier oil, and nallycondensing the vaporized fractions of said gasoline.

9. The process of refining pressure distillate that includes, subjectinggasoline-containing heated cracked petroleum distillate topolymerization by contacting the distillate in a treating zone withadsorptive material while heated to a temperature in excess of about 200F. but below the temperature of cracking, heating heavier oil having asubstantially higher boiling range than the gasoline content of saiddistillate to a temperature of at least about 300 F., mixing thepolymerized distillate with a larger quantity of the heated heavier oilto leave part of the gumforming and sulphur compounds of the gasoline insaid heavier oil, vaporizing said gasoline from the heavier oil,condensing a lower boiling fraction of the gasoline from the vapors,further depleting said lower boiling fraction of its gumforming andsulphur compounds by returning it to said treating zone wherein it isagain subjected to polymerization together with the pressure distillateflowing therethrough and later vaporized from said heavier oil, andfinally condensing vaporized fractions of said gasoline.

10. The process of rening pressure distillate that includes, subjectinggasoline-containing heated cracked petroleum distillate topolymerization by contacting the distillate with adsorptive materialWhile heated to a temperature in excess of about 200 F. but below thetemperature of cracking, heating heavier oil having a substantiallyhigher boiling range than the gasoline content of said distillate to atemperature of at least about 300 F., mixing the polymerized distillatewith a larger quantity of the heated heavier oil, passing the mixed oilsinto a separating zone and vaporizing said gasoline from at least aportion of said heavier oil to leave part of the gum-forrning andsulphur compounds of the gasoline in said heavier oil, removing saidportion of the heavier oil from the separating zone, separating avaporized higher boiling fraction of said gasoline from an unvaporizedlower boiling fraction thereof, heating said lower boiling fraction andcontacting it with adsorptive material, then mixing said higher boilingfraction with a larger quantity of heated heavier oil,

vaporizing said higher boiling fraction of the gasoline from the heavieroil admixed therewith, leaving additional gum-forming andsulphurcontaining compounds in the heavier oil, and nally condensingvaporized fractions of said gasoline. f

l1. The process of rening pressure distillate that includes, subjectinggasoline-containing heated cracked petroleum distillate topolymerization by contacting the distillate with adsorptive materialWhile heated to a temperature in excess of about 200 F. but below thetemperature of cracking, heating heavier oil having a substantiallyhigher boiling range than the gasoline content of said distillate to atemperature of at least about 300 F., mixing the polymerized distillatewith a larger quantity of the heated heavier oil, reducing the pressureof the mixed oils and passing them into a separating Zone wherein saidgasoline is vaporized from said heavier oil to leave part of thegum-forming and sulphur compounds of the gasoline in said heavier oil,removing the heavier oil from the separating Zone, separating a lowerboiling fraction of said gasoline from an unvaporized higher boilingfraction thereof, heating and contacting said higher boiling fraction ofthe gasoline with adsorptive material and then mixing said higherboiling fraction with heated heavier oil, vaporizing said higher boilinggasoline fraction from the heavier oil admixed therewith in a secondseparating zone and leaving additional gum-forming and sulphur compoundsin the last mentioned heavier oil, withdrawing the unvaporized heavieroil from said second separating zone, and finally condenslng thevaporized fractions of said gasoline.

WILLIAM T. HANCOCK.

